Defiant Prime Minister Tony Abbott yesterday insisted a challenge against his leadership was doomed to fail - and his government would not repeat the "chaos and instability" of previous administrations. With dismal ratings in opinion polls and a backbench disgruntled by policy backflips, two of Abbott's MPs declared they would call for a challenge to his stewardship of Australia at a meeting of the governing Liberal Party on Tuesday. But the conservative leader said he was expecting the so-called "spill motion" - aimed at toppling him and deputy Julie Bishop and triggering a new vote among Liberal parliamentarians for those positions - to fail. "Should this spill motion be defeated, as I expect, I will be taking that as a strong endorsement of the existing leadership team," he said. "The last thing any of us should want to do is to reproduce the chaos and the instability of the Labor years." Labor switched prime ministers twice in their last turn in government - first in 2010 when Julia Gillard removed Kevin Rudd, and then in 2013 when they changed back to Rudd. "We are not Labor ... and this Game of Thrones circus which the Labor Party gave us is never going to be reproduced by this coalition," Abbott said in reference to the TV fantasy drama in which characters vie for power. So far no one has stepped forward to contest the leadership should the backbenchers succeed in their push for a vote, likely to be decided in a secret ballot. Communications Minister Malcolm Turnbull, a millionaire who supports Australia becoming a republic, is considered a front runner while Bishop could also throw her hat into the ring. However Bishop said she didn't support the spill motion.